1. Field of Invention
The present invention generally relates to a flash memory data access method and a configuration employing the same, and more particularly, to an access method that is able to reduce the number of times of the flash memory block writing and a configuration employing the same.
2. Description of Related Art
Storage devices such as the hard disk or the soft disk drive are commonly used in computers as the mass storage device to store data. However, no matter whether hard disk or soft disk drive, a motor is mandatory to rotate the magnetic material to a specific location to store the data that is to be saved. If this kind of storage device is applied to the portable computers that are widespread used currently, the portable computer suffers not only from great power consumption of the batteries by the storage device, but also failure or even malfunction of the storage device caused by vibration.
Therefore, in order to meet the requirements of being light, thin, short and small as well as being portable, applying the solid state memory to the mass storage device will be a great choice because this kind of storage device does not have the problems mentioned above. Consequently, many related techniques for using the solid state memory to replace the rotating magnetic media had been proposed. All of these can be used to solve the problems mentioned above. Moreover, in these non-volatile memories, it is generally recognized that the flash memory related technique is the most mature art to replace the rotating magnetic media mentioned above to be the mass storage memory device, And so it is also the most probable candidate in the short term to replace the rotating magnetic media as the computer mass storage memory.
Furthermore, accompanying the development of related electronic products, the demand of portable electronic devices for flash memory has increased gradually. For example, the most popular electronic devices, such as the digital camera or the personal digital assistant (PDA), or even the mobile phone, need to use a large amount of mass storage media. However, since all the portable electronic devices mentioned above have the characteristic design of light, thin, short and small, the non-volatile memory is the only choice, and so flash memory is the most popular and most widespread memory product.
However, flash memory has its own limitations. Since flash memory is composed of a transistor memory cell, and the data access is performed via electron tunneling or erasing to achieve the operation of data saving or data erasing, a large current passes through the dielectric layer on the sideway of the floating gate electrode. Hence, all this kind of the memory has the limitation of a fixed number of erasing and writing times. That is, after a certain number of erasing and writing times, the memory cell will fail or malfunction. Moreover, the flash memory vendors all set the number of the erasing and writing times in such memory from 100 thousand to 1 million. Consequently, how to reduce the number of the erasing and writing times to increase the flash memory lifetime becomes a very important technology development trend.
Since the speed of the erasing operation is relatively slow, the memory operation efficiency can be significantly improved if the number of the erasing and writing times can be reduced.